Clarification of cane-sugar juice



Jan. 3, 192' I J. V. N. DQRR CLARIFICATION OF CANE SUGAR JUICE mvrzmoa Jomu V. N. Donn 525x1 6 azouwm warm xvi PEFS Filed Se t. 8

Patented Jan. 3,, 1928.

UNITED STATES PATENT OFFICE.

JOHN V. N. DORE, OF NEW OANAAN, CONNECTICUT, ASSIGNOB TO THE DORR COM.- PANY, OF NEW YORK, N. Y., A CORYORATION OF DELAWARE.

CLARIFICATION O1" CANE-SUGAR JUICE.

Application filed September 8, 1924 Serial No. 736,423.

My invention relates to the manufacture of-sugar and is especially directed to improvements in the clarification of sugar cane juice. It is applicable to the type of clarification process in which two successive defecation steps are employed, each followed by settling and decantation.

In this type of process the rich juice from the crusher and the firstmill or mills is defecated separately and passes to the first decantation unit or clarifier, where the mud is removed by sedimentation. The thin juice from succeeding. mills is defecated and treated in a second clarifier to remove the mud. Ordinarily the mud from the first clarifier is introduced with the thin juice into the second clarifier, while the overflow from the latter may be mixed with the feed to the first clarifier. These steps are embodied in the Petree process as set forth in United States Patent No. 1,266,882, in which the mud from the second clarifier is returned to the megass behind the mills which produce rich juice for the first defecation.

In certain plants objections have been raised to the return of mud to the megass on the ground that this step results in a loss in extraction. since a certain amount of sugar in solution is returned with the mud; but since the solids must be substantially dry for satisfactory disposal thereof, and in view of expense involved in operating filter presses as heretofore practiced, the advantages of returning the mud to the megass have outweighed any loss in extraction.

An object of my invention is to provide a method of handling the defecation mud that will reduce substantially any loss due to the return of the mud to the megass, and

which at the same time will substantially reduce the expense of dewatering the mud in filter presses. I have found that the mud produced by double defecation as above outlined possesses certain peculiar characteristics not found in ordinary defecation mud, which is well known to be slimy and very hard to filter. The second defecation mud however has a substantially different consistency;- and I have ascertained that it can be filtered much more readily than the ordinary mud. I therefore contemplate the use of filter presses or other filtration means for dewatering and washing the second clarifier mud. and have found that where presses are.

employed the number required is much smaller than that necessary for corresponding volumes of ordinary defecation mud.

It is however necessary to dispose of the solids in the mud, which is accomplished most conveniently by combining the solids with the spent megass, ordinarily use'd as fuel; and furthermore it is desirable to eliminate as far as possible the labor in cident to the use of plate and frame presses. I have provided a method of accomplishing either or both of these objects by employing a plate and frame press of the type in which the cake is removed by flushing with water or other suitable fluid. A press of this type is shown in United States Patents Numbers 798,200 and 905,341. The cake is naturally mixed with the flushing fluid and discharged in the form of a press mud which can readily be returned to the megass preferably in advance of the last mill.

This method of operation not only 'reduces very substantially the labor required in disposing of the defecation mud, but results in improved extraction. In the first place. a substantial part of the liquid in the mud,-which carries a certain amount of sugar, is extracted in the press, particularly when a wash is employed. The small amount of sugar remaining in the cake, which ordinarily is wasted, is taken up by the water used in flushing the press; and

since this water can conveniently be used for maceration, a certain amount of this residual sugar from the cake will be saved. It will of course be apparent that the sugar content of the water in the press mud will necessarily be less than that of the diluted juice in the megass at the point where such mud is returned Other features of my invention will be apparent to those familiar with this art, from the following detailed description in connection with the accompanying drawing, which comprises a diagrammatic flow sheet of one method of practicing my improved process.

My invention is a plicable to a plant having any number 0 mills; but for convenience I have illustrated an arrangement employing a crusher and three mills. In accordance with the usual practice in a double defecation process as above indicated, the i juice from the crusher and first mill 11 is collected in pan 12 and passes through the liming device 13 and heater 14 into the settling tank or clarifier 15. The clarifier is preferably of the continuous multiple unit I. type shown in United States Patents Numbers 1135,997 and 1,237,745. which produces a continuous overflow of clear juice and a.

continuous underflow of first clarifier mud. The juice from mill 16 passes through the II liming device 17 and heater18 into the second clarifier 19 preferably of the same type as clarifier' 15. The mud from the first clarifier is also fed to the second clarifier 19, preferably passing first through the limer 17 and heater 18. The overflow from the second clarifier 19 may be disposed of in various ways, one convenient arrangement being to mix it with the rich juice from pan 12.

Instead of sending the mud discharge from the second clarifier 19 to the megass, I force the mud into filter press 20 in the usual manner, removing a substantial part of the dilute juice therefrom as filtrate. This may be followed by a wash in the press in accordance with the usual practice.

As heretofore indicated I prefer to employ a press in which the cake is removed by sluicing with a suitable fluid. such as water, producing a fluid mud which may be disposed of as desired.

A convenient method of handling the filter press mud is illustrated in the drawing, and comprises the return of this mud to the megass at some point ahead of the last mill 21. With this arrangement the solids in the mud will be disposed of with the megass without any additional handling, an arrangement substantially more convenient than the handling of filter cake by the usual methods.

It is well recognized that maceration is controlled to a substantial extent by a number of factors including the capacity of the evaporators, the proportion of sugar in the maceration water, and the proportion of sugar in the dilute juice between the various mills. The process described produces a filtrate and a wash from the filter press 20, together with the filter press mud, all of which are available for maceration in addition to the dilute juice from the last mill 21. The point at which these fluids are returned as maceration water is an engineering problem in each particular installation. In the drawings I have shown the return of the filter press mud immediately in advance of the last mill 21, and the return of the fil trate from press 20 to the overflow from the second clarifier 10; but this arrangement can be varied in ways which will be obvious to those skilled in the art, depending partly upon conditions at each plant.

WVhile I have illustrated only three mills, producing rich juice, thin juice and the dilute juice ordinarily used for maceration respectively, it will be evident that any number of mills may be employed in each of these stages without affecting my invention. Moreover, while other types of clarifiers may conceivably be employed, the type illustrated has peculiar advantages in connection with this particular process, partly because it employs continuously operating mechanical means for sweeping the settled solids to the discharge, producing continuously a much thicker mud than the ordinary clarifier. The thickness of this mud renders the operation of the filter much more eficient than with ordinary clarifiers; and moreover, such mud has the unusual physical characteristics already indicated which make it much more suitable for filtration than ordinary mud.

It will be understood that for simplicity the usual intermediate apparatus such as strainers, pumps, etc., has been omitted for the sake of clearness, and that substantial variations in the arrangement shown may be made without departing from my invention as indicated in the following claims.

I claim:

1. In a process for the production of clarified juice from sugar cane in which mud from the defecation of rich juice is defecated with thin juice, the steps comprising filtra tion of the mud from the latter defecation in a filter pressand removal of the cake from the press by means of a fluid.

2. In a process for the production of clarified juice from sugar cane in which mud from the defecation of rich juice is defecated with thin juice, the steps comprising filtration of the mud from the latter defecation in a filter press, removal of the cake from the press by flushing the press with water, and returning the filter mud produced by the flushing operation to the megass in advance of the last mill.

In a process for the production of clarified juice from sugar cane in which mud from the defecation of rich juice is defecated with thin juice. the steps comprising filtration of the mud from the latter defecation in a filter press, washing the press cake, the filtrate and wash being kept separate, return of wash to the megass for maceration, removal of the cake from the press by flushing with water, and return of the resultant filter press mud to the megass.

4. In a process for the production of clarified juice from sugar cans in which the juice expressed from the cane is defecated and the resultant mud is separated therefrom, the steps comprising filtration of the mud in a filter press, removal of the cake from the tion apparatus comprising a plurality of 10 press by flushing with water, and return of superposed settling compartments with conthe resultant filter press mud to the megass tinuously operating means for sweeping the at a point in advance of the last mill. settled solids to a point of discharge, the

5 5. In a process for the production of claristeps comprising filtration of the mud from fied juicefrom sugar cane in which mud said apparatus in a filter press and removal 15 from the defecation of rich juice is defecated of the cake from said press by flushing with with thin juice, the mud from the second water. defecation being removed in a sedimenta- JOHN V. N1 DORR. 

